Middle-aged or older folks who ate as much as 3.5 ounces of chocolate a day seemed to receive heart health benefits, British researchers report in the June 16 issue of the journal Heart.

And most people in the study ate milk chocolate, generally considered less healthy than dark chocolate because it contains more sugar and fat, the researchers noted.

"People who want to eat chocolate should not be worried too much about their cardiovascular health," said study co-author Dr. Phyo Myint, chair of medicine of old age at the University of Aberdeen in Scotland. "We did not find any harmful effects of chocolate, if they want to enjoy chocolate now and again. The key is moderation."

While the study uncovered a link between chocolate and heart health, it didn't prove cause-and-effect.

The research team mainly based its findings on almost 21,000 adults taking part in a study that is tracking the impact of diet on the long-term health of 25,000 men and women in Norfolk, England.

Participants were monitored for nearly 12 years, on average, during which time 14 percent of them fell ill with either heart disease or stroke.

The researchers found that people who ate the most chocolate a day -- up to 3.5 ounces -- had a 14 percent lower risk of heart disease and a 23 percent lower risk of stroke than those who ate no chocolate.

The researchers then lumped the data in with nine other studies that measured chocolate consumption and heart disease. The combined pool involved nearly 158,000 people.

This analysis produced even stronger results. People who ate the most chocolate had a 29 percent reduced risk of heart disease and a 21 percent reduced risk of stroke, compared with those who ate the least. They also were 45 percent less likely to die from heart disease, heart attack or stroke.

Myint warned that the studies only looked at middle-aged and older people, not young adults or children.

"We don't know how this would affect children," he said.

These findings add to mounting evidence that chocolate appears to be heart-healthy, said Dr. Mark Urman, a preventive cardiologist at Cedars-Sinai Heart Institute in Los Angeles.

"But we still don't know for sure what specific part of chocolate, or parts of what's in chocolate, may be creating a benefit for heart health," Urman said.

But other ingredients in chocolate bars may also be good for your health, including milk and nuts, Myint said. In addition, chocolate contains certain fatty acids that might help heart health, Urman said.

Most previous research has shown benefits only from dark chocolate, but this latest study included any type of chocolate. Most opted for milk chocolate, the researchers found.

Myint and Urman cautioned that this observational study could not draw a direct cause-and-effect link, and said there might be other potential explanations for the benefits found.

For example, the researchers saw that people who ate chocolate tended to be in better health.

"These people who were high consumers of chocolate tend to be younger and physically more active, they tend to have less diabetes and be less obese," Myint said. "Although we control for these things, we can't be 100 percent sure whether we have adequately adjusted for them."

The findings also relied on people's own reports of their eating habits, which can be inaccurate, Myint said.

Finally, Urman said that people should not rely on chocolate to lower their risk of heart disease or stroke.

"It's important to have it be part of an overall balanced, heart-healthy diet," he said. "There's ultimately no one magic bullet out there that's going to cure everything or prevent anything. It's an odds game, and the more you put in your favor, the better your odds are."